Nozzle attachment for use in die casting



p 19, 1967 J. G. MEZOFF ETAL 3,342,373

NOZZLE ATTACHMENT FOR USE IN DIE CASTING Filed Sept. 15, 1964 /n er/ gas INVENTORS. J G-Me off' //0r7 J. Mayer flTTORNEY United States Patent Ofifice 3,342,378. Patented Sept. 19, 1967 3,342,378 NOZZLE ATTACHMENT FOR USE IN DIE CASTING John G. Mezoif, Bay City, and Elton J. Mayer, Sanford,

Mich., assignors to The Dow Chemical Company, Midland, Mich., a corporation of Delaware Filed Sept. 15, 1964, Ser. No. 396,541 3 Claims. (Cl. 222152) This invention relates in general to die casting and more particularly relates to a novel nozzle attachment device for use with casting machines, through which molten metal is discharged into a utilization device such as the shotwell of a die casting machine.

In die casting, intermittent predetermined amounts of molten metal, called shots, are pumped from a supply of the metal through a heated transfer line or delivery pipe and dispensed into a plunger-equipped shotwell of a die casting machine. This plunger, coordinated with the intermittent action of the pump, is then actuated to inject the shot of metal into a closed, multi-pieced, die assembly. The injected shot, after a few seconds, solidifies and is ejected from the open die. With the die closed the sequence is repeated to cast additional pieces at a rapid rate.

A long standing problem in the art of die casting light metals, and particularly with magnesium, has been the frequent plugging of the conventional goosenecked shaped discharge end of a heated delivery pipe, which is connected to a pump means for supplying molten metal to and through said delivery pipe. This plugging was caused, at least in part, by a gradual build-up of oxidation products, such as oxides and nitrides, and the like in and around said discharge end, or in the various apparatus attached thereto. This was encountered notwithstanding that inert gas, such as argon or nitrogen, was normally introduced as an inert atmosphere in and about said discharge end in an attempt to avoid formation of said build-up. The splashing discharging metal, moreover, also frequently caused plugging of the outlet opening at said end through which the inert gas was introduced thus promoting the formation of build-up. Accordingly, it was heretofore frequently necessary, fater, for example, from about 3 to 4 eight-hour consecutive working shifts, to interrupt or shut down the die casting operation altogether to allow cleaning or replacement of said discharge end section of the molten metal delivery pipe. Such interruptions are not only time consuming but are costly. There is a need in the art, therefore, for a nozzle device, attachable as a unit to the delivery pipe, which will significantly minimize these difiiculties in die casting and permit an essentially uninterrupted and prolonged, thus more efficient, die casting operation.

An object of the present invention, therefore, is to provide a new and novel nozzle device for use in die casting light metals which minimizes the difliculties and problems heretofore encountered a to plugging during the discharging of molten metal from a delivery pipe.

Another object is to provide such a nozzle device for use in die casting magnesium, which is easily attachable as a unit to the discharge end of a molten metal delivery pipe and which markedly reduces the aforesaid build-up at said end, thus permitting a significantly longer uninterrupted and continuous die casting operation.

Other objects and advantages of the invention will become apparent as the description of the invention proceeds.

In general the novel apparatus of the present invention comprises primarily a three legged T-shaped nozzle, two legs of which, when the nozzle is positioned for use, are essentially vertically disposed while the remaining leg is essentially horizontally disposed. Hereinafter the present application will be referred to either as a lateral T or nozzle. The legs of the T-shaped nozzle are disposed to form an apparatus wherein molten metal flowing into the nozzle through one leg thereof will be in a lateral T relationship to the leg of the apparatus wherefrom said metal exits, while inert gas is introduced by means located in the remaining leg into confluence with the exiting molten metal at an acute angle to the flow of metal into the exit leg. The first leg of the apparatus, termed hereinafter as the molten metal exit portion or leg and the second leg, termed hereinafter as the gas-introducing portion or gas leg, are preferably on a common longitudinal axis and of the same approximate cross-section size, the latter portion being adapted with a gas inlet opening as aforesaid at or near its upper end. The third leg, termed as the molten metal receiving portion or receiving leg, forms at the juncture of all said legs preferably an acute angle or lateral T with the other two legs such that molten metal from the receiving portion or leg is directed downwardly into the exit portion in confluence with a constant front of inert gas. Preferably, however, the receiving leg is extended in a downwardly concaved return-bend manner so as to enable a level of molten metal of minimum surface area to be maintained therein at its apex. The inert gas is introduced under pressure from a gas supply means into the gas-introducing portion or leg of the present inventive nozzle apparatus. In general, then, the exit leg and receiving leg are so-disposed, adapted, or .positioned, so as to define the molten material flowing through said receiving leg in a lateral T relationship with said exit leg while inert gas is constantly being introduced into the nozzle in confluence with the molten metal flow in the exit leg.

The invention will be more readily understood from a reading of the following detailed description with reference to the accompanying multifigured drawing showing specific embodiments of the broad invention, in which corresponding parts are designated by similar reference numbers, and wherein:

FIG. 1 is a side elevational View, in section, showing a preferred embodiment of the apparatus of the invention in a position, attached to a delivery pipe, as would be used to discharge metered shots of molten metal from the end of a delivery tube.

FIG. 2 is a side elevational view, in section, showing another embodiment of the invention similarly as in FIG. 1;

FIG. 3 is an end elevation of the device shown in FIG. 2.

FIG. 4 is a side elevational view showing a further embodiment of the present invention.

Referring now to the drawings, there is shown in FIG. 1 a preferred embodiment of the apparatus of the present invention comprising a lateral T-shaped element which is cylindrical in cross section throughout each of its legs and attached by a Weldment 10 to the discharge end 12 of a molten metal delivery pipe. The apparatus has a gas-introducing leg 14, an exit leg 16 for discharging molten metal, both said legs being on a common longitudinal axis, and a molten metal receiving leg or portion 18, one end of which remote from the other legs is attached to said delivery pipe. The gas leg 14 is equipped with a gas inlet means 20 for introducing inert gas into the apparatus (indicated by arrows), said inlet comprising a conduit 22 extending into the upper end of said gas leg 14', the end of said conduit 22 internal to the gas leg 14 being provided with a plurality of uniformly spaced holes 24 transversely disposed for introducing a constant front of gas in the apparatus. The conduit is held by a threaded cap 26. The receiving portion or leg 18 comprises an arcuately shaped section '28 which is downwardly concaved thus enabling a level 30 of molten metal of minimum surface area .to be maintained preferably at or near the apex thereof. The end of said receiving portion 18 remote from the other legs is disposed lower with respect to its other end so as to permit a reservoir of molten metal to be maintained in said receiving portion 1-8 which is contained at the aforesaid level 30 depending on said apex. Accordingly, when a predetermined or other amount of molten metal is pumped, this level overflows and is downwardly directed in a lateral tee obtuse angle manner in confluence with the inert gas into said exit leg of the apparatus, and from thence into a utilization device such as, for example, a shotwell of a die casting machine.

The embodiment of the present invention illustrated in FIG. 2 being of a hemi-sigmoidal retrorse shape, cylindrical in cross section, and though similar to that of FIG. 1, has the advantage in that its receiving leg 18 is constructed angularly throughout thus being easier to fabricate. However, any embodiment of the invention as shown (that is, that of FIGS. 1, 2, or 4) produces a lateral tee type flow of metal, together with inert gas as described hereinbefore, thus obtaining; the desirable results of prolonged casting operations without interruption as hereinbefore discussed.

The embodiment of the present apparatus shown in FIG. 4, instead of illustrating the gas-introducing leg 14 and the exit leg 16 as a continuous cylindrical tube with the receiving leg connection midpoint thereto as in FIGS. 1 and 2, shows the exit leg '16 as an extension of the arcuate segment of the receiving leg 18 with the gasintroducing leg 14 being attached to the receiving leg and exit leg extension thereto and communicating therewith, so as to be in line with the longitudinal axis of the exit leg extension. Though both the exit leg and gas leg have been shown and described herein as being on a common longitudinal axis, either may deviate somewhat provided the longitudinal axis of the receiving leg, or the direction of flow of metal therefrom, at the juncture of all the other legs does not preferably form an angle with the longitudinal axis of the gas leg greater than 90 and preferably not more than about 45. The opening of the gas leg at the juncture of all the legs is, moreover, preferably located above that of the receiving leg when the nozzle is in operation. The use of various deflection bafiles (not shown) within the apparatus may be beneficially employed to aid in better directing the lateral tee flow of molten metal therethrough. The cross-sectional size of the legs is preferably equal.

In general, the length of the exit leg 16 is determined so as toprovide definite direction to the molten metal being discharged therefrom into said utilization device. The gas-introducing leg 14 on the other hand must be extended, that is, be long enough so that the inlet means for the gas which is located at or near its upper end will not be plugged by any splashing metal during the die casting operation. Normally, the length of both the exit and gas legs may be approximately equal. The receiving portion 18 or third leg is adapted primarily for the purpose of providing in conjunction with the exit leg a definite downward direction to the molten metal in a lateral tee relationship therewith as it is pumped through the nozzle, for example, in intermittent shots by the aforesaid molten metal pump. Its length, therefore, apart from its function is not particularly limited. Preferably, however, the receiving portion 18 is extended as illustrated in FIGS. 1 and 2 in a downwardly concaved return-bend shape so as to enable a level 30 of molten metal of minimum surface area to be maintained therein at its apex, during the brief periods between dispensing of said intermittent shots. The end of the receiving leg 18 remote from the other legs of the nozzle is adapted to be attached as aforesaid to the discharge end 12 of the delivery pipe, thereby providing means to attach the entire nozzle apparatus of the present invention as a unit to the delivery pipe and pump means 32.

If desired, the exit leg portion and gas-introducing portion of the apparatus may be positioned off center, that is, tilted, as shown in FIG. 3 for convenience in discharging molten metal to either one side or the other of the apparatus rat-her than being in line with the receiving portion. The out-of-line angle will preferably vary between the angles of 45 to to the horizontal.

Notwithstanding the embodiment of the invention employed, the uniform front of inert gas is provided by means of an inert gas inlet or conduit extending into the upper end of the gas-introducing portion of the apparatus, the inlet being adapted to introduce said gas above and into confluence with the molten metal as a substantially constant uniform front by means, for example, of a plurality of uniformly spaced lateral holes located near the end of the inlet conduit and positioned with reference to their longitudinal axis at an angle to the longitudinal axis of said conduit of not preferably greater than about 90. A downwardly traversing front of inert gas (such as indicated in by the arrows in FIG. 1) through the apparatus and in and about the receiving leg thereof is thereby produced to substantially minimize the formation of oxides and the like heretofore caused by burning of unprotected molten metal. It should be noted that for the sake of uniformity the introduction of inert gas must be constant and not intermittent.

The apparatus itself is normally constructed as a unit being adapted for attachment :at the free end of the receiving leg to the discharge end of the delivery tube such as, for example, by welding, bolting, or by means of a slip joint.

The present novel apparatus may conveniently and economically be made using, for example, mild steel and welded joints or may be constructed of stainless steel such as Number 430 stainless.

The construction of the present apparatus together with the uniform protective front of insert gas formed therein essentially completely eliminates plugging of the inert gas outlet due to splashing of metal and due to build-up of oxides and other materials because of burning of the metal in the nozzle. Accordingly, the present novel apparatus permits significantly longer periods of operation in die casting without expensive and time consuming interruptions, breakdowns, and the like. In addition, when the die casting operation is temporarily stopped, the inert gas flow may be continued to protect the molten metal in the nozzle from oxidation.

The following examples dramatically illustrate not only the use of the present invention but also particularly the marked increase in the uninterrupted die casting operation time using the present apparatus. These examples are illustrative and are, therefore, not to be construed as limiting the invention thereto.

Example I In order to simulate a die casting operation and illustrate the present invention, a nozzle apparatus in accordance with the present invention and similar to that shown in FIG. 1 of the drawing was constructed of 2 inch diameter mild steel pipe. The nozzle was then Welded to the discharge end of a delivery pipe, the other end of pipe being attached to a molten metal pump. After preheating, the pump was immersed in a pot containing a supply of the molten magnesium to be pumped at a temperature of from about 1210" to 1220 F. The delivery pipe and nozzle extended out of the pot and was heated and maintained at a temperature of about 1200 F. Nitrogen gas was introduced into the nozzle at a rate of about 4 c.f.m. The pump was then operated to dispense about 90 intermittent shots per hour, each shot so-dispensed being about 4 seconds in duration. The molten metal pumped was recycled back into the pot. This pumping operation was carried on for the equivalent of 15 consecuctive eight-hour shifts, whereupon, the shot duration reached 7 seconds. Pumping having been terminated, the nozzle was examined and found to contain a build-up of oxides and nitrides such that cleaning of the nozzle was required.

Example I shows that a die casting operation by use of the present nozzle attachment to the delivery pipe provides an outstanding increase in uninterrupted operation time.

Example II A nozzle apparatus similar to that of Example I was similarly employed in an actual die casting operation under similar conditions. The die casting operation was carried on for 14 consecutive eight-hour shifts before the nozzle had to be cleaned or replaced. This is in contrast, for example, to the heretofore 3-4 shift duration obtainable in die casting operations employing conventional nozzles.

As the examples show, the present invention provides a new and novel but yet simple nozzle attachment device for use in die casting which permits uninterrupted prolonged die casting operations heretofore unobtainable in in the die casting art.

The present invention may be modified and changed without departing from the spirit or scope thereof and it is understood that we limit ourselves only as defined in the appended claims.

We claim:

1. A nozzle device adapted to be coupled to a molten metal delivery pipe for use in die casting operations wherein molten metal is intermittently dispensed as shots from a supply of said molten metal through a heated delivery pipe by means of a pump submerged in said supply in communication with said delivery pipe; the nozzle consisting essentially of a three legged internally communicating substantially T-shaped apparatus having a molten metal exit leg, an extended gas-introducing leg including means for introducing inert gas into the device, and a molten metal receiving leg shaped in a downwardly concaved return-bend manner to enable a level of molten metal to be maintained therein at its apex and adapted to direct said shots of molten metal in a positive downwardly direction into the molten metal exit leg.

2. In die casting wherein intermittent shots of molten metal are dispensed from the discharge end of a heated delivery pipe communicating with pump means in contact with a supply of the molten metal to be dispensed; the improvement comprising a nozzle apparatus attachable as a unit to said discharge end, said nozzle comprising a three legged lateral T-shaped device, the legs of which internally communicate at a juncture, said nozzle having a leg for introducing inert gas into the nozzle being extended in length to avoid plugging thereof by molten metal, an exit leg for dispensing molten metal from the nozzle, said exit and gas legs, when in the operating position, being essentially vertically disposed on a common longitudinal axis, and a molten metal receiving leg comprising a downwardly concaved arcuate segment essentially horizontally disposed when in the operating position along its segmental length, said exit and receiving legs being positioned to define a flow of metal therethrough at an obtuse angle, the end of said receiving leg remote from the juncture of all said legs being adapted for attachment to the discharge end of the delivery pipe.

3. In die casting wherein intermittent shots of molten metal are dispensed from the discharge end of a heated delivery pipe communicating with pump means in contact with a supply of the molten metal to be dispensed; the improvement comprising a lateral T-shaped nozzle attachment for use at the discharge end of said pipe, having three legs internally communicating with one another at a juncture, the first leg being adapted to introduce an inert gas into the nozzle above and in confluence with said molten metal and extended in length to prevent plugging by molten metal, the second leg being adapted to dispense molten metal from the nozzle, said exit leg and gas leg when in the operating position being essentially vertically disposed on a common longitudinal axis, the third leg, essentially horizontally disposed and constructed in a hemi-sigmoidal retrorse shape, being adapted to receive and maintain a level of molten metal therein of minimum surface area, said exit and receiving legs being positioned to define a flow of metal therethrough at an obtuse angle, with an acute angle being formed between the gas leg and the flow of metal out of the receiving leg, the end of the receiving leg remote from the juncture of all the legs being adapted for attachment to the discharge end of said delivery pipe.

References Cited UNITED STATES PATENTS 271,359 1/1883 Pike 137604 2,504,805 4/1950 Clipson 239433 2,745,153 5/1956 Burkett 2279 3,252,187 5/ 1966 Burkett 2270 J. SPENCER OVERHOLSER, Primary Examiner. R. D. BALDWIN, Assistant Examiner, 

1. A NOZZLE DEVICE ADAPTED TO BE COUPLED TO A MOLTEN METAL DELIVERY PIPE FOR USE IN DIE CASTING OPERATION WHERE IN MOLTEN METAL IS INTERMITTENTLY DISPENSED AS SHOTS FROM A SUPPLY OF SAID MOLTEN METAL THROUGH A HEATED DELIVERY PIPE BY MEANS OF A PUMP SUBMERGED IN SAID SUPPLY IN COMMUNICATION WITH SAID DELIVERY PIPE; THE NOZZLE CONSISTING ESSENTIALLY OF A THREE LEGGED INTERNALLY COMMUNICATING SUBSTANTIALLY T-SHAPED APPARATUS HAVING A MOLTEN METAL EXIT LEG, AND EXTENDED GAS-INTRODUCING LEG INCLUDING MEANS FOR INTRODUCING INERT GAS INTO THE DEVICE, AND A MOLTEN METAL RECEIVING LEG SHAPED IN A DOWNWARDLY CONCAVED RETURN-BEND MANNER TO ENABLE A LEVEL OF MOLTEN METAL TO BE MAINTAINED THEREIN AT ITS APEX AND ADAPTED TO DIRECT SAID SHOTS OF MOLTEN METAL IN A POSITIVE DOWNWARDLY DIRECTION INTO THE MOLTEN METAL EXIT LEG. 